Radiolab: (So Called) Life

In a world where biology and engineering intersect, how do you decide what's "natural"?

Biotechnology is making it easier and easier to create new
forms of life, but what are the consequences when humans play with
life? We travel back to the first billion years of life on Earth,
take a look at how modern engineers tinker with living things, and
meet a woman who could have been two people.